I looked at an 89 Firebird Formula with 104k on it yesterday. The body is VERY nice and it had new exhaust and some cheapo chrome rims. The guy said it has a 305 TBI in it that runs well and I'm guessing a 700-R4. My questions are....

What kind of power can I expect from this car?

Is TBI reliable at all?

How will the gas mileage be on this car?

Are there any aftermarket parts for TBI?

Would this motor even be worth building?

I really don't know anything about TBI and the last car I had was an 86 Z with a 350 TPI from a Vette, so I know it's going to be a dissapointment going to a TBI 305, but it's still a very nice car and I could pick it up for around $1000. If I can get some time and space around here I would like to build a 350 TPI for it, but I dunno if thats gonna happen.

 

TBI is the crappiest fuel injection to try and mod. may as well throw ur money into the wind b/c its not worth to put mods on IMO.i would say buy it if ur gonna plan on changing the intake before u start to heavily mod the car.

as far as i know the TBI's are pretty reliable. i have a 95 Silverado and a 94 S-10 both w/ TBI's and are doing fine.

 

TBI is really reliable. My 142k car hasn't given me a problem in the 6k I've owned it. Gas mileage isn't bad, as long as your foot isn't always in the throttle I averaged 16 with the M5 in the city, probably 17-18 with the 6-speed---I turn like 1500rpm everywhere. On the highway, I've read of 6-speed LO3 guys getting upwards of 30 on a long trip

I wouldn't try to build it up, unless you're one of those "gotta be different" guys. Like everyone always says, which is very true, "Whatever you do to a 305, if you did it to a 350, you'd be faster." Well something like that but you get the idea. I'd go with building a 350 TPI like you said. Good luck, and for $1k I'd buy that car right up.

-Corey

 

I also noticed a WS6 badge on the dash. I think if I'm going to build up a 350 TPI for the car, it's GOT TO be a hardtop though. My Camaro used to twist soo badly and handle like ****.

 

TBI's are extremly reliable, my dads truck has a tbi 5.0 in it with 294k miles on the clock, only probs was a leak in the intake an the occasional fuel pump.........but tbi's are not worth throwing alot of $ into, like you said, build up a tpi 305/350 if u want good power

 

I'm thinking maybe I'll get it and store it for the winter and drive my VW for the winter and just go to junkyards and get a whole TPI setup. Would I be better off just getting a TPI car though?

 

easier? yes....but wheres the fun in that?!

 

two words...
CARB SWAP!!

 

even with a carb on an LO3 its still not capable of a ton of power.........

 

I know it's not a 350, but it's still a V8, which means nice torque, and plenty of aftermarket parts. Granted, there aren't many INDUCTION parts, but everything else is good.


3 Main things to Upgrade: Exhaust, Cam, Heads

After those three, you've got a decent contender. You can always do the 454 TB swap for more fuel.

If you wanna go on the cheap side, you can get a used cam (LT1) used head (Alum L98) and then cheap headers, and you're almost up to the power of a stock LT1. You'll be just over 250. Get it chipped and do some suspension work and you'll take out stock LT1s.

Not that bad of an engine.

 

Yeah, if you want MPFI, stick with a 350 TPI car.

As far as a 305 TBI keeping up with even a stock LT1, I doubt it. Not saying that it can't be done, but I wouldn't waste my time trying. How many stock LT1's are there anyways?

 

Yeah, I'm most likely going to go with a late model 350 with a complete TPI set up with post 87 L98 heads. I want it basically stock and I have a real limited budget, but I was very impressed when I had my 350 TPI car and besides K&N's, some ignition components, and a 3 inch exhaust it was all stock. I also just found an 87 IROC for about $1500, so I may check into that.

 

wow, so many misconseptions about TBI, this is unreal.

1) TBI is very relialable.
2) parts are cheaper than TPI parts. you can use any 4bbl carbed intake, and a $10 adaptor plate. or upgrade to a 4bbl TBI unit.
3) it is NOT the tbi holding the LO3 back. it is the heads/cam, if you toss a set of TPI heads, and a little better cam, you can easily get as much power as TPI, it will probably actualy make more HP, but not have the torque spike at 3500rpm that you get from the tunned runners, that makes all the TPI people think their cars are fast

now, on a 350 TBI engine, if you use the l98 heads, i would suggest getting single plane carbed intake, with a high-flow TBI unit, and a descent cam, 325-350 HP is very easily doable and i am sure it will be for alot less money than trying to do it on a TPI car. it will need computer work, just like a SD tpi system would, being a MAP based computer, it just isn't as friendly as a MAF system is.

as for the potential power. the holley 670cfm TBI is rated at 1.5"hg , the same as the carb, the airflow limits would allow you over 400hp throught the 2bbl unit. the real limit is the ammout of fuel you can deliver via 2 injectors the limit of the injectos seems to be between 350-400hp. with the 4bbl TBI units, 500+ hp is doable.

 

Thank you very much, this puts the Firebird up there as a definite maybe, especially since i saw the WS6 badge.

When I had my Camaro with the 350TPI I got around 20 mpgs, most of my driving is highway. Should I expect more, less, the same, from the TBI?

Also, with 104k miles on it, are there any specific points I should be checking?

 

on the free way, i get over 30mpg, with 3.42 rear gears.

same stuff to check as any other SBC.